OnJava8-Examples/concurrent/ThrowsChecked.java

// concurrent/ThrowsChecked.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
import java.util.stream.*;
import java.util.concurrent.*;

public class ThrowsChecked {
  class Checked extends Exception {}
  static ThrowsChecked nochecked(ThrowsChecked tc) {
    return tc;
  }
  static ThrowsChecked
  withchecked(ThrowsChecked tc) throws Checked {
    return tc;
  }
  static void testStream() {
    Stream.of(new ThrowsChecked())
      .map(ThrowsChecked::nochecked)
      // .map(ThrowsChecked::withchecked);        // [1]
      .map(tc -> {
        try {
          return withchecked(tc);
        } catch(Checked e) {
          throw new RuntimeException(e);
        }
      });
  }
  static void testCompletableFuture() {
    CompletableFuture
      .completedFuture(new ThrowsChecked())
      .thenApply(ThrowsChecked::nochecked)
      // .thenApply(ThrowsChecked::withchecked);  // [2]
      .thenApply(tc -> {
        try {
          return withchecked(tc);
        } catch(Checked e) {
          throw new RuntimeException(e);
        }
      });
  }
}